JP5620162B2 - Manufacturing method of heating element - Google Patents

Description

  The present invention relates to a method for manufacturing a heating element.

  As a prior art relating to a method of manufacturing a heating element using heat generated by an oxidation reaction between oxygen in the air and an oxidizable metal, for example, Patent Document 1 discloses heat generation using an ink-like or cream-like heating composition. A body manufacturing method is described. The method for producing a heating element described in Patent Document 1 stirs activated carbon, a thickener, a surfactant, a pH adjuster, salt and iron powder in the order of each predetermined compounding ratio on a base material sheet as a packaging material. In addition, an ink-like or cream-like exothermic composition obtained by stirring and kneading while adding water is further laminated to produce a heating element.

However, the method for producing a heating element described in Patent Document 1 stirs and kneads salt (electrolyte) and iron powder at the same time, although there is an effect of suppressing heat generation due to excess water when the exothermic composition is formed by stirring and kneading. Therefore, the paint attached to the paddle and tank wall of the kneader causes a violent oxidation reaction by losing moisture, so the manufacturing equipment must use expensive materials with high corrosion resistance such as titanium, which is very expensive. Large capital investment is required.
Moreover, since the manufacturing method of the heat generating body described in Patent Document 1 is agitated and kneaded with salt (electrolyte) and iron powder at the same time, it is not possible to suppress sedimentation or water separation of the heat generating composition, and the heat generating composition is dispersed. It was difficult to maintain sex.

  The present applicant previously applied a coating solution containing oxidizable metal particles, fiber material, water and a water retention agent and having a water content of 40 to 75% by weight on a support to contain water. After forming a molded body and dehydrating the water-containing molded body to a predetermined moisture content, the dehydrated water-containing molded body is heated and dried to a predetermined moisture content to obtain an intermediate molded body. A method for producing a heat-generating molded body was proposed in which a predetermined amount of an aqueous electrolyte solution was applied to the body to form a heat-generating molded body (Patent Document 2). According to this method for producing an exothermic molded body, since the electrolyte is not contained in the coating liquid, when the coating liquid is applied or when an intermediate molded body is obtained by dehydration and drying, It is difficult for the metal particles to oxidize and the dispersibility of the exothermic composition can be maintained.

  However, the exothermic molded body manufacturing method of Patent Document 2 requires a dehydration process and a heat drying process, which tends to increase the manufacturing process.

JP-A-9-75388 JP 2004-143232 A

Therefore, the subject of this invention is providing the manufacturing method of the heat generating body which can eliminate the fault which the prior art mentioned above has.

  The present invention provides a heating element in which a layer of a heat generating composition containing particles of an oxidizable metal, an electrolyte and water is provided on a base sheet made of a fiber sheet containing particles of a superabsorbent polymer and a fiber material. An electrolyte addition step of adding an electrolyte aqueous solution containing the electrolyte to one surface of the base sheet, and an addition surface of the electrolyte aqueous solution in the base sheet of the oxidizable metal not containing the electrolyte The present invention provides a method for producing a heating element comprising a coating process for coating a paint containing particles.

  According to the heating element manufacturing method of the present invention, the oxidation of the oxidizable metal particles being manufactured by the aqueous electrolyte solution is suppressed as much as possible, the dispersibility of the heating composition is maintained, and a heating element having good heating characteristics is manufactured. can do. The manufacturing method of the heating element of the present invention can keep the manufacturing process compact.

FIG. 1 is a schematic diagram illustrating a longitudinal cross-sectional structure of a base sheet used in Example 1. FIG. FIG. 2 is a schematic view showing an example of a manufacturing apparatus preferably used for manufacturing the heating tool of the present invention.

Hereinafter, the present invention will be described based on preferred embodiments thereof.
The heating tool manufactured by the manufacturing method of the heating tool of the present invention includes a heating element and a packaging material as its constituent members. The heating element manufactured by the method for manufacturing a heating element of the present invention is preferably used as a heating element of the heating tool, for example. A heating element as a constituent member of a heating tool is a member that generates heat in the heating tool. On the other hand, the packaging material of the heating tool is a member that surrounds the entire heating element and forms the outer surface of the heating tool of the present invention.

First, the heating element manufactured by the manufacturing method of the heating element of the present invention will be described.
A heating element manufactured by the method for manufacturing a heating element of the present invention includes a base sheet and a layer of a heating composition (hereinafter also referred to as a “heating layer”) provided on the base sheet. The base sheet is composed of a fiber sheet containing superabsorbent polymer particles and a fiber material. The heat generating layer includes particles of an oxidizable metal.

  The base sheet made of a fiber sheet may be (a) one sheet in a state where the particles of the superabsorbent polymer and the fiber material are uniformly mixed. In the base sheet, (b) the superabsorbent polymer particles are mainly present in a substantially central region in the thickness direction of the base sheet, and the particles are substantially present on the surface of the base sheet. It can also be one-ply with a structure that is not. Further, the base sheet may be (c) a laminate of two fiber sheets in which particles of a superabsorbent polymer are arranged between the same or different fiber sheets containing a fiber material. Of these base sheets that can take various forms, it is preferable to use the base sheet having the form (b) from the viewpoint of easily controlling the moisture content of the heat generating layer.

As the fiber material contained in the base sheet made of a fiber sheet, both hydrophilic fibers and hydrophobic fibers can be used, but it is preferable to use hydrophilic fibers. As the hydrophilic fiber, any of natural fiber and synthetic fiber can be used.
By using hydrophilic fibers as the constituent fibers of the base sheet, there is an advantage that hydrogen bonds are easily formed with the oxidizable metal contained in the heat generating layer, and the shape retention of the heat generating layer is improved. . In addition, the use of hydrophilic fibers also has the advantage that the water absorption or water retention of the base sheet is improved and the water content of the heat generating layer can be easily controlled. From these viewpoints, cellulose fibers are preferably used as the hydrophilic fibers. Chemical fibers (synthetic fibers) and natural fibers can be used as the cellulose fibers.

  As chemical fibers of cellulose, for example, rayon and acetate can be used. On the other hand, various vegetable fibers such as wood pulp, non-wood pulp, cotton, hemp, wheat straw, hemp, jute, kapok, palm, rush and the like can be used as the natural cellulose fiber. Of these natural cellulose fibers, it is preferable to use wood pulp from the viewpoint of easily obtaining thick fibers. The use of thick fibers as the cellulose fibers is advantageous from the viewpoints of water absorption or water retention of the base sheet, retention of the heat generating layer, and the like.

  In particular, it is preferable to use a bulky cellulose fiber as the cellulose fiber. By using the bulky cellulose fiber, it becomes easy to make the inter-fiber distance of the constituent fibers in the base sheet suitable. As specific examples of the bulky cellulose fiber, (a) the fiber shape has a three-dimensional structure of a twisted structure, a crimped structure, a bent and / or branched structure, or (b) the fiber roughness is 0.2 mg / m or more. Or (c) those in which the intramolecular and intermolecular molecules of the cellulose fiber are crosslinked.

  Specific examples of the fiber having a three-dimensional structure such as a twisted structure, a crimped structure, a bent structure and / or a branched structure of (a) above include chemical pulp obtained by decomposing wood by chemical reaction, mechanical pulp, Pulp decomposed by treatment (beating) or pulp obtained by combining chemical reaction and mechanical treatment can be used.

  The fiber (b) is a bulky state in which cellulose fibers are accumulated, thereby reducing the movement resistance of the liquid and increasing the permeation speed of the liquid. When the coating of the heat generating composition is applied to the base sheet in the production process, the moisture in the heat generating composition is easily transferred into the base sheet, so that the moisture content of the heat generating layer can be controlled. It becomes easy. In addition, a bulky network structure that can maintain the solid content of the paint constituting the heat generating layer is easily formed. From these viewpoints, the fiber roughness of the fiber (b) is preferably 0.2 to 2 mg / m, particularly preferably 0.3 to 1 mg / m.

  The fiber roughness is used as a scale representing the fiber thickness in fibers having non-uniform fiber thickness, such as wood pulp. For example, a fiber roughness meter (FS-200, KAJANNIELECTRONICSLTD. ). Examples of cellulose fibers having a fiber roughness of 0.2 mg / m or more include softwood kraft pulp (“ALBACEL” (trade name) manufactured by Federal Paper Board Co. and “INDORAYON” (trade name) manufactured by PT Inti Indorayon Utama. )] And the like.

The fiber (b) preferably has a roundness of the fiber cross section of 0.5 to 1, particularly 0.55 to 1. By using the cellulose fiber having such roundness, the movement resistance of the liquid in the base sheet is further reduced, and the passing speed of the liquid is further increased. The method for measuring roundness is as follows. The fiber is sliced perpendicular to the cross-sectional direction so that the area does not change, and a cross-sectional photograph is taken with an electron microscope. The cross-sectional photograph is analyzed by an image diffractometer [“Avio EXCEL” (trade name) manufactured by Nippon Avionics Co., Ltd.], and the cross-sectional area and circumference of the measurement fiber are measured. Using these values, the roundness is calculated using the following formula. The roundness is an average value obtained by measuring 100 arbitrary fiber cross sections.
Roundness = 4π (cross-sectional area of measurement fiber) / (peripheral length of cross-section of measurement fiber) ²

  When wood pulp is used as the bulky cellulose fiber, the cross section of the wood pulp is generally flattened by delignification treatment, and most of the roundness is less than 0.5. In order to make it 0.5 or more, for example, the wood pulp may be mercerized to swell the cross section of the wood pulp. Examples of commercially available mercerized pulp include “FILTRANIER” (trade name) manufactured by ITT Rayonier Inc. and “POROSANIER” (trade name) manufactured by the same company.

  The crosslinked cellulose fiber as the fiber (c) is preferable because it can maintain a bulky structure even in a wet state. Examples of the method for crosslinking the cellulose fiber include a crosslinking method using a crosslinking agent. Examples of such crosslinking agents include N-methylol compounds such as dimethylolethyleneurea and dimethyloldihydroxyethyleneurea; polycarboxylic acids such as citric acid, tricarballylic acid and butanetetracarboxylic acid; polyols such as dimethylhydroxyethyleneurea A cross-linking agent for polyglycidyl ether compounds. The amount of the crosslinking agent used is preferably 0.2 to 20 parts by weight with respect to 100 parts by weight of the cellulose fiber. The crosslinked cellulose fiber has a fiber roughness of preferably 0.1 to 2 mg / m, particularly preferably 0.2 to 1 mg / m. The cross-linked cellulose fiber preferably has a roundness of the fiber cross section of 0.5 to 1, particularly 0.55 to 1. Examples of commercially available crosslinked cellulose fibers include “High Bulk Additive” manufactured by Weyerhaeuser Paper Co.

  Among the fibers (a) to (c) described above, particularly when the fiber (c) is used, the integrity of the base sheet and the heat generating layer is enhanced, and the advantageous effect that the heat generating layer is less likely to fall off. Is played. Further, the heating element becomes flexible, and there is an advantageous effect that the fitting property is improved when the heating tool of the present invention is attached to an object to be attached, for example, the skin or clothing of a human body. Surprisingly, it is worth noting that the flexibility of the heating element is maintained even after the end of heat generation.

  The above-mentioned various hydrophilic fibers preferably have a fiber length of 0.5 to 6 mm, particularly 0.8 to 4 mm, from the viewpoint of easy production of a substrate sheet by a wet method or a dry method.

  In addition to the above-described hydrophilic fibers, heat-fusible fibers may be blended in the base sheet as necessary. By blending this fiber, the strength of the substrate sheet in a wet state can be increased. The compounding amount of the heat-fusible fiber is preferably 0.1 to 10% by mass, particularly 0.5 to 5% by mass, based on the total amount of fibers in the base sheet.

  As described above, the base sheet made of the fiber sheet contains particles of the superabsorbent polymer. The location of the superabsorbent polymer particles in the base sheet is as described above. As the superabsorbent polymer, it is preferable to use a hydrogel material that can absorb and hold a liquid having a weight 20 times or more of its own weight and can be gelled. The shape of the particles can be spherical, massive, grape bunches, fibers and the like. The particle diameter of the particles is preferably 1 to 1,000 μm, particularly preferably 10 to 500 μm. Specific examples of superabsorbent polymers include starch, crosslinked carboxylmethylated cellulose, polymers or copolymers of acrylic acid or alkali metal acrylates, polyacrylic acid and salts thereof, and polyacrylate graft polymers. Is mentioned. The superabsorbent polymer particles are preferably bonded to the fiber material contained in the base sheet. Further, a liquid material containing a polymerizable monomer and / or a polymerized product of the monomer may be attached to a web made of a fiber material and polymerized to form particles of a superabsorbent polymer.

  The ratio of the superabsorbent polymer in the base sheet is 10 to 70% by weight, particularly 20 to 55% by weight, and the viewpoint of making the water absorption or water retention of the base sheet suitable and the heat generating layer This is preferable from the viewpoint of controlling the water content. This ratio is a value measured for the base sheet in a dry state before the heat generation layer is formed on the base sheet.

The base sheet preferably has a basis weight of 10 to 200 g / m ² , particularly 35 to 150 g / m ² . By setting the basis weight of the base sheet within this range, sufficient strength of the base sheet in a wet state can be secured, and water absorption or water retention of the base sheet should be suitable. Can do. On the other hand, the basis weight of the superabsorbent polymer contained in the base sheet is preferably 5 to 150 g / m ² , particularly 10 to 100 g / m ² . By setting the basis weight of the superabsorbent polymer within this range, the water absorption or water retention of the base sheet can be further improved. Moreover, it becomes easier to control the moisture content of the heat generating layer. These basis weights are values measured for the base sheet in a dry state before the heat generation layer is formed on the base sheet.

  The substrate sheet can be produced by, for example, the airlaid method when it is in the form of (a). In the case of (b), it can be produced, for example, by the wet papermaking method described in JP-A-8-246395 related to the previous application of the present applicant. In the case of (c), it can be produced by the airlaid method or the wet papermaking method.

  The base sheet is provided with a heat generating layer on at least one surface thereof. The heat generating layer may be provided only on one side of the base sheet, or may be provided on both sides. The heat generating layer is a water-containing layer containing particles of an oxidizable metal, an electrolyte, and water. The heat generating layer may further contain a reaction accelerator. The heat generating layer may be present on the base sheet, or the lower part of the heat generating layer may be embedded in the base sheet. Among these, it is preferable that the lower part of the heat generating layer is buried in the base material sheet. That is, it is preferable that a part of solid content constituting the heat generating layer is carried in a three-dimensional network formed on the fiber sheet constituting the base sheet. Since part of the heat generation layer is embedded in the base sheet, the unity of the heat generation layer and the base sheet is increased, and the heat generation layer is removed from the base sheet (before, during, and after use). Effectively prevented.

  Examples of the oxidizable metal contained in the heat generating layer include iron, aluminum, zinc, manganese, magnesium, calcium and the like. The particle size of the oxidizable metal particles can be, for example, about 0.1 to 300 μm. As the reaction accelerator, it is preferable to use a reaction accelerator that has a function as an oxygen retention / supply agent for an oxidizable metal in addition to acting as a moisture retention agent. Examples of the reaction accelerator include activated carbon (coconut shell charcoal, charcoal powder, calendar bituminous coal, peat, lignite), carbon black, acetylene black, graphite, zeolite, perlite, vermiculite, silica and the like. As the electrolyte, an electrolyte capable of dissolving an oxide formed on the surface of the oxidizable metal particles is used. Examples thereof include alkali metal, alkaline earth metal or transition metal sulfates, carbonates, chlorides or hydroxides. Among these, chlorides of alkali metals, alkaline earth metals or transition metals are preferably used from the viewpoint of excellent conductivity, chemical stability and production cost, and particularly sodium chloride, potassium chloride, calcium chloride, magnesium chloride, chloride. Ferrous and ferric chloride are preferably used.

On the condition that the basis weight of the base sheet is in the above-mentioned range, the amount of the oxidizable metal in the heating element is 100 to 3,000 g / m ² , particularly 200 to 1,500 g, expressed in basis weight. / M ² is preferable from the viewpoint of securing a sufficient calorific value. The amount of the reaction accelerator in the heating element is preferably 4 to 80 g / m ² , particularly 8 to 50 g / m ² , from the viewpoint of maintaining stable heat generation for a long time. For the same reason, the amount of the electrolyte in the heating element is preferably ⁴ to 40 g / m ² , particularly 5 to 30 g / m ² . These basis weights are values in the case where one layer of heat generation layer is formed on one side of the base sheet. Therefore, when the heat generating layers are formed on both sides of the base sheet, these basis weights are double the above-mentioned values. Further, the basis weight is appropriately adjusted according to the specific application of the heating element.

As described above, the heat generating layer is in a water-containing state. The moisture content of the heat generating layer is preferably 5 to 50% by mass, particularly 6 to 40% by mass. By setting the moisture content of the heat generating layer within this range, the fluidity of the heat generating layer decreases, and consequently the viscosity decreases. As a result, as described later, even if a sheet having air permeability is arranged on the upper side of the heat generating layer, the inconvenience that the air permeability of the sheet is impaired by sticking of the heat generating layer is less likely to occur. The moisture content of the heat generating layer is measured with respect to a portion located above the surface of the base sheet. Therefore, the site | part embedded in the base material sheet among heat_generation | fever layers is excluded from the measuring object of a moisture content. A specific method for measuring the moisture content of the heat generating layer is as follows. That is, the exothermic layer at a portion located above the surface of the base sheet is taken out in a nitrogen environment, and its weight is measured. Then, it puts into a drying furnace for 2 hours at the temperature of 105 degreeC of a vacuum state, remove | eliminates a water | moisture content, measures a weight again, and measures a moisture content.
The moisture content of the heat generating layer is a value per heat generating layer.

By setting the moisture content of the heat generating layer within the above range, the heat generating layer is effectively prevented from sticking to the breathable sheet disposed thereon. There may be a concern that the heat generation characteristics are reduced due to the decrease in the amount of the above. However, in the present invention, since the base sheet contains water and water is supplied from the base sheet to the heat generating layer during heat generation, the heat generation characteristics are not deteriorated. In particular, since the base sheet contains a superabsorbent polymer, and the release of water from the superabsorbent polymer proceeds gradually, the heat generation characteristics are stable over a long period of time. From these viewpoints, the proportion of water in the heating element, that is, the moisture content of the heating element is preferably 10 to 60% by mass, particularly 12 to 50% by mass. The specific method for measuring the moisture content of the heating element is as follows. In other words, the weight of the heating element was measured in a nitrogen environment, and then placed in a drying oven at a temperature of 105 ° C. in a vacuum state for 2 hours to remove moisture, and the weight was measured again, and the difference weight was included as the moisture content. Calculate the amount of water.
The moisture content of the heating element described above is a value when one heating layer is formed on the base sheet, but the above range is satisfied even when the heating layer is formed on both sides of the base sheet. preferable.

  In the heating element, when the heating layer is formed only on one surface of the base sheet, the moisture content on the side of the base sheet where the heating layer is not provided is the moisture content of the heating layer. Is preferably lower. In this way, on the side where the heat generating layer is formed, moisture supply for heat generation is performed on the heat generating layer, while on the side where the heat generating layer is not provided, the base sheet and Adhesion with the covering sheet is prevented, and an advantageous effect is obtained that the air flow in the heating tool is hardly hindered. In order to achieve such a moisture content relationship, it is advantageous to use, for example, a substrate sheet having the above-described structure (b) or (c). In the base sheet having the structure of (b) or (c), since the superabsorbent polymer particles are unevenly distributed in the central region in the thickness direction, a heat generating layer is formed only on one surface of the base sheet. This is because water permeation is prevented at the site where the superabsorbent polymer particles are unevenly distributed, so that the water content on the opposite side of the base sheet can be kept low.

  In the heating tool manufactured by the heating tool manufacturing method of the present invention, the heating element described above is surrounded by the packaging material. This packaging material preferably includes a first cover sheet and a second cover sheet. The first cover sheet is disposed on the heat generating layer side of the heat generating element. The second covering sheet is disposed on the side of the heating element where the heating layer is not formed (when the heating layer is formed only on one side of one base sheet) or on the side of the heating layer. (For example, when a heat generating layer is formed on both surfaces of one base sheet).

  The first cover sheet and the second cover sheet each have an extended area extending outward from the periphery of the heating element, and the extended areas are joined to each other. This joining is preferably an annular continuous airtight joining surrounding the heating element. The packaging material formed by joining both covering sheets has a space for accommodating a heating element therein. A heating element is accommodated in this space. In the case where the joints between the extension regions are annular and continuous airtight joints, it is ensured that solids (for example, oxidizable metal particles) are removed from the heating element contained in the packaging material. Since it is prevented, it is preferable.

It is preferable that the heating element accommodated in the packaging material is not fixed to the packaging material. That is, the movement of the heating element is preferably not restricted by the packaging material and can be moved independently of the packaging material. In this case, for example, when a pressure-sensitive adhesive is applied to the second covering sheet in the packaging material to form a pressure-sensitive adhesive portion, and the heating tool of the present invention is attached to the user's skin or the like via the pressure-sensitive adhesive portion, Even if the second cover sheet is pulled due to the operation, the pulled state does not propagate to the heating element, so that the solid content (for example, oxidizable metal particles) from the heating element Dropout is effectively prevented.
Further, since the heating element is not constrained, it can move independently from the packaging material, and since it is difficult to adhere to the covering sheet, the air permeability of the covering sheet is not hindered. Moreover, the flow of air around the base sheet is not inhibited in the packaging material, and a good exothermic reaction can be obtained.

A part of the first covering sheet in the packaging material has air permeability, or the whole has air permeability. As described above, since the first covering sheet is disposed to face the heat generating layer in the heat generating portion, the first covering sheet has air permeability, so that the supply of oxygen to the heat generating layer is smooth. Performed, and stable heat generation is maintained for a long time. From this point of view, the air permeability of the first covering sheet (JIS P8117 B type, hereinafter referred to as the measured value of this method when referred to as air permeability) is 1 to 50,000 seconds / (100 ml · 6.42 cm ² ), In particular, it is preferably 10 to 40,000 seconds / (100 ml · 6.42 cm ² ). As the first covering sheet having such air permeability, for example, a porous sheet made of a synthetic resin having moisture permeability but not water permeability is preferably used. When using such a porous sheet, various fiber sheets such as needle punched nonwoven fabric and air-through nonwoven fabric are laminated on the outer surface of the porous sheet (the surface facing outward in the first covering sheet). Thus, the texture of the first cover sheet may be enhanced.

As the second covering sheet in the packaging material, an appropriate one is selected according to the structure of the heating element. The second cover sheet is preferably a breathable sheet having a lower breathability than the first cover sheet from the viewpoint of stably generating water vapor through the first cover sheet. In particular, when the heat generation layer of the base sheet is not located on the second covering sheet side, the second covering sheet is preferably a sheet having lower air permeability than the first covering sheet. The “sheet with low air permeability” as used herein refers to a non-breathable sheet that is partially breathable but has a lower degree of breathability than the first covering sheet and does not have breathability. Includes both cases. When the second cover sheet is a non-breathable sheet, examples of the non-breathable sheet include a synthetic resin film, a needle punched non-woven fabric on the outer surface of the film (the surface facing outward in the second cover sheet), A composite sheet obtained by laminating various fiber sheets including a nonwoven fabric such as an air-through nonwoven fabric can be used. When the second cover sheet is a breathable sheet, the same breathable sheet as that of the first cover sheet can be used. In this case, the air permeability of the second cover sheet is 200 to 150,000 seconds / (100 ml · 6.42 cm ² ), particularly 300 to 100, provided that the air permeability of the second cover sheet is lower than that of the first cover sheet. It is preferably 000 seconds / (100 ml · 6.42 cm ² ). When the second cover sheet is a breathable sheet, stable heat generation can be performed even in a use state in which the outer surface of the first cover sheet is in close contact with the user's skin or clothes, for example.

In the heating element, the heating layer may be formed on only one side of one base sheet, or may be formed on both sides. In the case of forming on both surfaces, for example, a base material sheet to which a coating material described later is applied can be formed through a second coating material coating process by inverting the upper and lower surfaces with a turn bar or the like.
Moreover, the heating element accommodated in the heating tool may be one or may be accommodated in a multilayer state in which a plurality of heating elements are laminated.

The heating tool manufactured by the manufacturing method of the present invention can generate water vapor from the side where the first cover sheet is disposed. In order to enable the generation of water vapor, (b) on the premise that the heat generating layer contains a large amount of water, (b) a method of adjusting the proportion of each component constituting the heat generating layer, (c) Examples thereof include a method of adjusting the air permeability of the first and second covering sheets surrounding the heating element, and a method of using (d) (b) and (c) in combination. In the heating tool of the present invention, a large amount of water can be retained when the base sheet contains hydrophilic fibers. Due to this, the heating tool of the present invention can generate a large amount of water vapor. Moreover, in the heating tool, since the base sheet contains a hydrophilic polymer in addition to containing the hydrophilic fiber, the base sheet can hold a large amount of water also by this, As a result, a large amount of water vapor can be generated. The ratio of each component constituting the heat generation layer (b) is as described above. The air permeability of the first and second covering sheets in (c) is also as described above. The amount of water vapor that is released through the first cover sheet ^{4, 0.01~0.8mg / (cm 2 · min} ) in accordance with the measuring method described later, especially 0.03~0.4mg / (cm ² · min) It is preferable that

  When both the first covering sheet and the second covering sheet have air permeability, the air permeability value of the first covering sheet 4 is made smaller than the air permeability value of the second covering sheet ( That is, it is preferable that the amount of water vapor released through the first cover sheet is greater than the amount of water vapor released through the second cover sheet 5 by increasing air permeability. As long as the amount of water vapor released through the first cover sheet is greater than the amount of water vapor released through the second cover sheet, it is impeded that water vapor is released through the second cover sheet. I can't.

The amount of water vapor released through the first cover sheet is measured as follows. That is, heating is started by bringing the heating tool into contact with air at 20 ° C. and 65% RH. Immediately place the heating tool on a pan balance capable of measuring 1 mg, and then measure the mass for 15 minutes. Steam generated from the following equation when the mass at the start of measurement is Wt ₀ (g), the mass after 15 minutes is Wt ₁₅ (g), and the steam generation area of the heating tool is S (cm ² ) Calculate the amount of
Water vapor release [mg / (cm ² · min)] = {(Wt ₀ −Wt ₁₅ ) × 1000} / 15S

  The first covering sheet in the packaging material may have an adhesive layer formed by applying an adhesive on the outer surface thereof. The pressure-sensitive adhesive layer is used for attaching the heating tool of the present invention to human skin or clothing. As an adhesive which comprises an adhesion layer, the thing similar to what was used until now in the said technical field including a hot-melt adhesive can be used. From the viewpoint of not impairing the air permeability, it is preferable to provide an adhesive layer on the peripheral portion of the first cover sheet.

Next, preferred embodiments of the above-described heating element and heating tool manufacturing method, that is, the heating element manufacturing method and heating tool manufacturing method of the present invention will be described.
A preferred embodiment of the method for producing a heating element of the present invention comprises (1) an electrolyte addition step and (2) a coating step which will be described below. A preferred embodiment of the method for manufacturing a heating tool of the present embodiment includes (3) a heating element covering and sealing step in which the manufactured heating element is surrounded by a packaging material to form a heating tool after the manufacturing process of the heating element. To do.

(1) Electrolyte addition process In the electrolyte addition process which is one process of the manufacturing process of a heat generating body, the electrolyte aqueous solution containing an electrolyte is added to one surface of a base material sheet. For example, the aqueous electrolyte solution is continuously applied on one surface of a base sheet made of a continuous long material. The method of adding the electrolyte aqueous solution includes dripping or spraying with a nozzle, application with a brush, die coating, etc., but the production facility by preventing the electrolyte aqueous solution from scattering to the surroundings, blocking the electrolyte aqueous solution discharge port, and contacting with the paint From the viewpoint of preventing contamination, it is preferable to drop or spray using a nozzle.

In the aqueous electrolyte solution to be added, the electrolyte is preferably contained in an amount of 3 to 35% by mass, particularly 5 to 30% by mass. The added amount of the electrolyte (in terms of solid content) is 0.5 to 15 parts, particularly 1 to 10 parts, with respect to 100 parts of the oxidizable metal particles added to the same area in the coating step described later. It is preferable.
The addition (spreading) basis weight of the aqueous electrolyte solution is preferably 30 to 400 g / m ² , particularly 50 to 300 g / m ² .

  The aqueous electrolyte solution added in the electrolyte addition step is preferably an aqueous solution in which the proportion of the electrolyte is higher than the proportion of the electrolyte with respect to the total amount of electrolyte and water contained in the heating element. Further, as the electrolyte aqueous solution to be added in the electrolyte addition step, the mass of the superabsorbent polymer contained in the base sheet in the saturated absorption amount of the superabsorbent polymer measured using JIS K 7224 using the electrolyte aqueous solution. It is preferable to add a larger amount of the aqueous solution than the amount multiplied by. JIS K 7224 is a water absorption rate test method for highly water-absorbent resins, and is a test method for water absorption rate by the vortex method, which is known as a method for indicating the ability of fixing a liquid when the water-absorbing polymer is forcibly exposed to the liquid It is. Superabsorbent resin is synonymous with superabsorbent polymer. Here, “using JIS K 7224” means that the adjustment and procedure of a sample, a test solution, a test instrument, and the like are followed. The saturation absorption amount of the superabsorbent polymer is measured as follows, including unspecified contents such as measurement of the absorption amount.

[Measurement Method of Saturated Absorption of Superabsorbent Polymer Using JIS K 7224]
100 mL of an electrolyte aqueous solution 50 g having the same concentration as the electrolyte aqueous solution to be added in the electrolyte addition step and a magnetic stirrer chip (center diameter 8 mm, both ends diameter 7 mm, length 30 mm, surface is coated with fluororesin) The beaker is placed on a magnetic stirrer (HPS-100 manufactured by ASONE). The rotational speed of the magnetic stirrer is adjusted to 600 ± 60 rpm, and the aqueous electrolyte solution is stirred. Next, 2 g of the superabsorbent polymer contained in the base sheet is introduced into the liquid at the center of the vortex of the aqueous electrolyte solution being stirred. Up to this point, the operation conforms to JIS K 7224 (1996). The amount of absorption of the superabsorbent polymer 10 minutes after charging the superabsorbent polymer is measured, and the amount of absorption per part by weight of the superabsorbent polymer is determined from the measured amount of absorption of the superabsorbent polymer. Weigh a bag-like 100 x 100 mm size polyester mesh (mesh size 255 / 25.4 mm) in advance, and absorb the electrolyte aqueous solution 10 minutes after charging the electrolyte aqueous solution into the polyester mesh bag. The superabsorbent polymer was put in, dehydrated with a centrifugal dehydrator at 2,000 rpm for 10 minutes, and the weight of the polyester mesh and the superabsorbent polymer was measured together. From the measured value, the absorption amount of the high molecular weight polymer is calculated by subtracting 2 g of the superabsorbent polymer before absorption and the weight of the polyester mesh. This determined value is taken as the saturated absorption amount of the superabsorbent polymer at the concentration of the aqueous electrolyte solution added in the electrolyte addition step. In the measurement, n = 5 is measured, the values at each of the upper and lower points are deleted, and the average value of the remaining three points is taken as the measured value. These measurements are performed at 23 ± 2 ° C. and a humidity of 50 ± 5%, and the samples are stored for 24 hours or more in the same environment before the measurement.

(2) Coating process In the coating process, which is one step of the heating element manufacturing process, (1) the surface of the base sheet after the electrolyte addition process does not contain an electrolyte and contains an oxidizable metal. Apply paint containing particles. For example, the paint is continuously applied on the addition surface to which the electrolyte aqueous solution is continuously added. Here, “without electrolyte” means an electrolyte added for the purpose of dissolving an oxide formed in particles of an oxidizable metal, and does not mean that it does not contain all electrolytes. This means that the electrolyte added in the electrolyte addition step to be described later is substantially not included, and the chlorine component contained in the water when tap water is used is not the electrolyte referred to here.

  The paint usually contains a reaction accelerator and water in addition to the oxidizable metal particles. Moreover, you may mix | blend a thickener and surfactant from a viewpoint of improving the dispersibility of the solid content in a coating material. The coating material containing these components is continuously applied on one surface of a base sheet made of a continuous long material, for example. Moreover, as a coating method of a coating material, various well-known coating methods can be especially used without a restriction | limiting. For example, roll coating, die coating, screen printing, roll gravure, knife coating, curtain coater and the like are used. Die coating is preferable from the viewpoint of easy application, easy control of the application amount, and uniform coating of the paint.

In the coating material used for forming the heat generating layer, it is preferable that the reaction accelerator is contained in an amount of 1 to 20 parts, particularly 2 to 14 parts, when the oxidizable metal particles are 100 parts. It is preferable that water is contained in 25 to 85 parts, particularly 35 to 75 parts. The thickener is preferably contained in an amount of 0.05 to 10 parts, particularly 0.1 to 5 parts. The surfactant is preferably contained in an amount of 0.1 to 15 parts, particularly 0.2 to 10 parts. Further, water is preferably contained in an amount of 18 to 48% by mass, particularly 23 to 43% by mass, assuming that the total mass of the paint is 100%.
The coating basis weight of the paint is preferably 150 to 4,600 g / m ² , particularly preferably 300 to 2,200 g / m ² .
The viscosity of the coating is 500 to 30,000 mPa · s at 23 ° C. and 50 % RH, and particularly preferably 1,000 to 15,000 mPa · s. For measurement of the viscosity, a No. 4 rotor of a B type viscometer was used.

According to the method for producing a heating element of the present invention comprising (1) an electrolyte addition step and (2) a coating step, a layer (heating layer) of a heating composition containing particles of an oxidizable metal, an electrolyte and water, A heating element provided on a base sheet made of a fiber sheet containing superabsorbent polymer particles and a fiber material can be continuously produced.
Since the coating material contains substantially no electrolyte, oxidation of the oxidizable metal powder does not proceed before the electrolyte addition step. Therefore, no special allowance is required in order to shield the oxidizable metal powder from the air in the coating process. In addition, the progress of the oxidation reaction during storage of the paint can be suppressed, and heat loss can be reduced.
Further, since the coating material contains no electrolyte, the components of the coating material before coating or during coating maintain good dispersibility. For example, even if the paint is allowed to stand before coating, it is difficult for the oxidizable metal particles to agglomerate in the paint to cause the aggregate to settle or separate.
According to the method for manufacturing a heating element of the present invention, as described above, since the electrolyte is not actively contained in the paint, it was created while the paint was being created in the manufacturing equipment such as a tank. While applying the paint, it is difficult for the oxidation reaction to occur on the wall surface of the paddle or tank of the kneading machine, and therefore, it is possible to minimize the use of expensive materials with high corrosion resistance in the manufacturing equipment.

  Further, according to the method for manufacturing a heating element of the present invention, the aqueous electrolyte solution added first is present in the base sheet, and then the coating containing the particles of the oxidizable metal is applied, whereby the oxidizable metal. The aqueous electrolyte solution can be uniformly contacted with the particles, and a heating element with little loss of heat generation can be produced.

  In particular, when an electrolyte aqueous solution having a concentration higher than the ratio of the electrolyte to the total amount of electrolyte and water contained in the manufactured heating element is added to the base sheet containing the superabsorbent polymer particles in the electrolyte addition step. This makes it difficult for the superabsorbent polymer to absorb the aqueous electrolyte solution, and tends to exist uniformly throughout the substrate sheet. In particular, a higher amount of the electrolyte aqueous solution than the amount obtained by multiplying the saturated absorption amount of the superabsorbent polymer measured using JIS K 7224 by the mass of the superabsorbent polymer contained in the base sheet is obtained. By adding to the base sheet containing these particles, the aqueous electrolyte solution that is not absorbed by the superabsorbent polymer is more likely to be present uniformly throughout the base sheet. Next, by applying the paint, the oxidizable metal particles can be brought into uniform contact with the electrolyte aqueous solution uniformly throughout the base sheet, and a heating element with less heat loss can be produced. . Even if the electrolyte aqueous solution having such a high concentration is added in advance, a paint containing water is added thereafter, and the aqueous electrolyte solution and the paint are mixed, whereby the concentration of the electrolyte aqueous solution is lowered. Therefore, the absorption performance of the superabsorbent polymer is increased, and the finally obtained heating element has a moisture concentration suitable for the heating of the oxidizable metal particles.

  From the viewpoint of uniformly dispersing the aqueous electrolyte solution over the entire base sheet and obtaining a predetermined exothermic temperature during use as described above, the aqueous electrolyte solution added in the electrolyte addition step is the total amount of electrolyte and water contained in the heating element. 10 to 80%, particularly 20 to 50% is particularly preferable with respect to the electrolyte. In addition, the electrolyte aqueous solution added in the electrolyte addition step is an electrolyte aqueous solution in an amount 1 to 10 times the amount obtained by multiplying the saturated absorption amount of the superabsorbent polymer by the mass of the superabsorbent polymer contained in the base sheet. It is preferable to add 1.5 to 6 times the amount of the aqueous electrolyte solution.

  Further, in the method for producing a heating element of the present invention, since the heating element is produced using a substrate sheet containing superabsorbent polymer particles, the heating element is produced using a substrate sheet not containing superabsorbent polymer particles. Compared with the method of manufacturing the process, it is not necessary to have a dehydration process or a heat drying process, the manufacturing process can be made compact, and the oxidation of the exothermic substance in the manufacturing process can be suppressed as much as possible.

The manufacturing method of the heating element of the present invention is from the other side of the base sheet (the surface opposite to the addition surface, hereinafter also referred to as the non-addition surface) after coating the coating on the addition surface of the electrolyte aqueous solution. By conducting suction, particles of the oxidizable metal are taken into the fiber material of the base sheet, thereby increasing the integrity of the paint layer or the heat generating layer and the base sheet, and the heat generating layer from the base sheet. Dropout (before use, during use, after use) is effectively prevented.
The suction force in the case of suction in this way is preferably 100 to 10,000 Pa, particularly 500 to 5,000 Pa. The suction force can be measured by attaching a manostar cage to the box in the suction conveyor.

(3) Covering step When a heating element made of a continuous long object is manufactured by the above operation, the heating element is covered with a packaging material in a heating element covering and sealing step following the manufacturing process of the heating element. Prior to this operation, it is preferable to produce a heating element for each leaf by cutting a heating element made of a continuous long object in the width direction. Next, while running the heating element of each leaf in one direction at a predetermined interval, the first covering sheet made of a continuous long object is disposed on the side where the heating layer is formed, and on the other side, Similarly, a second covering sheet made of a continuous long object is disposed. Subsequently, the extension area | region from the heat generating body in a 1st coating sheet and a 2nd coating sheet is joined by a predetermined joining means. Joining is performed outside the left and right side edges and outside the front and rear edges of the heating element. Examples of the bonding means include heat fusion, ultrasonic bonding, and adhesion using an adhesive.

  When the first covering sheet is disposed on the heat generating layer, the moisture content of the heat generating layer is reduced due to the absorption of the superabsorbent polymer and the fluidity is decreased. Even if the sheet is arranged, the inconvenience that the heat generating layer sticks to the first covering sheet is avoided. As a result, the air permeability of the first cover sheet is successfully maintained.

  In this manner, a continuous long object in which a plurality of heating tools are connected in one direction is obtained. By cutting this continuous long object across the width direction between adjacent heating elements, the intended heating tool is obtained. In the next step, the heating tool is hermetically housed in a packaging bag having oxygen barrier properties.

  In the above-described method, means for keeping the production line in a non-oxidizing atmosphere may be used as necessary in order to suppress oxidation of the oxidizable metal during the production process.

The heating tool of the present invention produced in this way is applied directly to the human body or applied to clothing and is suitably used for warming the human body. Examples of the application site in the human body include the shoulder, neck, eyes, waist, elbow, knee, thigh, lower leg, abdomen, lower abdomen, hands, and soles. Further, in addition to the human body, the present invention is applied to various articles and suitably used for heating and keeping warm.
Moreover, the heat generating body manufactured by this invention can also be used for the heat generating tool of another structure other than the heat generating part of the heat generating tool of this invention, and another use. When used for heating the human body, the first covering sheet that generates water vapor is applied toward the skin side (human body side).

  FIG. 2 shows an example of a manufacturing apparatus preferably used for manufacturing the heating tool of the present invention. The apparatus includes an electrolyte addition unit 30, a paint coating unit 20, a first cutting unit 40, a re-pitch unit 50, a covering unit 60, a sealing unit 70, and a second cutting unit 80.

  The electrolyte addition unit 30 includes a spray nozzle 31 that sprays an aqueous electrolyte solution. Further, an endless belt 22 of a wire mesh that faces the opening of the spray nozzle 31 and circulates in the direction of the arrow is also provided. The base sheet 1 made of a continuous long material fed from the base roll 1A of the base sheet is conveyed from the electrolyte adding unit 30 to the paint coating unit 20 by the endless belt 22, and a spray nozzle is formed on one surface thereof. The electrolyte aqueous solution 3 is sprayed from 31 nozzle holes. By spraying the electrolyte aqueous solution 3, the electrolyte aqueous solution is uniformly dispersed over the entire base sheet 1 (the entire area in the plane direction and the entire area in the thickness direction). The spray nozzle 31 may be a nozzle that drops an aqueous electrolyte solution.

  The paint coating unit 20 includes a die coater 21. A suction box 23 is provided immediately after the die coater 21 with an endless belt 22 interposed therebetween. The base material sheet after the addition of the aqueous electrolyte solution is conveyed from the electrolyte addition unit 30 to the paint coating unit 20 by the endless belt 22 and is directed to the surface of the base sheet by the die coater 21 toward the addition surface of the aqueous electrolyte solution. The coating 2 containing the oxidizable metal particles 2a is applied to form a heat generating layer. When the base material sheet 1 is transported in the paint coating unit 20, the suction box 23 may be operated to stabilize the transport, and the coated paint 2 may be sucked. The coated paint is mixed with the aqueous electrolyte solution contained in the base sheet, and the base sheet absorbs moisture, so that the concentration is adjusted, and the electrolyte layer has a suitable electrolyte concentration for heat generation. it can. By applying the paint after the addition of the aqueous electrolyte solution, the heat generating composition and the electrolyte are easily in contact with each other without unevenness, and a heating element with little loss of heat generation can be manufactured.

  When the heating element 10 made of a continuous long object is formed in this way, the heating element 10 is cut in the first cutting part 40 in the width direction. The first cutting unit 40 includes a rotary die cutter 42 having a cutter blade 41 on the peripheral surface and an anvil roll 43. Cutting is performed by the continuous long heating element 10 passing between the two members, whereby the heating element 10 of each leaf is obtained.

  The cutting of the heating element 10 made of a continuous long object may be performed so as to extend in the width direction of the heating element 10. For example, the heating element 10 can be linearly performed in the width direction of the heating element 10. Or it can cut so that a cutting line may draw a curve. In any case, it is preferable to employ a cutting pattern that does not cause trimming by cutting.

  The heating element 10 that has become a leaf is changed in pitch in the front-rear direction in the conveying direction by the endless belt 51 provided in the re-pitch portion 50, and the heating elements 10 that are adjacent to each other are rearranged at a predetermined distance. As such a re-pitch mechanism, a conventionally known one can be used without particular limitation.

  The re-pitched heating element 10 is conveyed to the covering section 60 and is entirely covered by the first covering sheet 4 made of a continuous long object and the second covering sheet 5 also made of a continuous long object. The first cover sheet 4 covers the side of the heat generating element 10 where the heat generating layer is formed, and the second cover sheet 5 covers the side of the heat generating element 10 where the heat generating layer is not formed. While maintaining this covering state, the heating element 10 is introduced into the sealing portion 70 by the endless belt 61 provided in the covering portion 60. The sealing part 70 includes a first roll 72 having a seal convex part 71 on the peripheral surface and a second roll 74 having a seal convex part 73 on the peripheral surface. Both rolls 72 and 74 are arranged in a positional relationship such that the axial directions thereof are parallel and the seal bars 71 and 73 of the rolls 72 and 74 abut each other or a predetermined clearance is generated between them. Has been. In the sealing part 70, the extended part of the 1st and 2nd coating sheets 4 and 5 extended from the front and rear, right and left of the heat generating body 10 is joined by heat sealing. This joint is a continuous airtight joint surrounding the heating element 10 or a discontinuous joint surrounding the heating element 10.

  In this manner, a continuous long object in which a plurality of heating tools are connected in one direction is obtained. The continuous long object is cut in the width direction in the second cutting portion 80. The second cutting unit 80 includes a rotary die cutter 82 having a cutter blade 81 on the peripheral surface and an anvil roll 83. Cutting is performed by passing the continuous long object between the two members, whereby the intended heating tool 100 is obtained. In the cutting, when the cutting line of the heating element 10 in the first cutting part 40 described above is, for example, a straight line, the cutting line in the main cutting part 80 is also preferably a straight line. Moreover, when the cutting line of the heat generating body 10 in the 1st cutting part 40 is a curve, it is preferable to make the cutting line in this cutting part 80 into the curve which followed it.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” and “part” mean “% by mass” and “part by mass”, respectively.

[Example 1]
(1) Preparation of aqueous electrolyte solution and paint A 5% sodium chloride aqueous solution was prepared as an aqueous electrolyte solution.
A paint was also prepared. The paint includes 100 parts by mass of an oxidizable metal (iron powder average particle size 45 μm), 8 parts by mass of a reaction accelerator (activated carbon average particle size 42 μm), 0.2 parts by mass of a thickener (gua gum), a surfactant ( (Polycarboxylic acid type polymer surfactant) 0.2 parts by mass and 60 parts by mass of water are blended. The viscosity of the obtained paint was 6,500 mPa · s. The viscosity was measured using a No. 4 rotor of a B-type viscometer in an environment of 23 degrees and 50% RH .

(2) Preparation of substrate sheet The substrate sheet shown in FIG. 1 was used. This base material sheet 1 was produced according to the method described in JP-A-8-246395. In the base sheet 1, the sodium polyacrylate-based superabsorbent polymer particles 12 are mainly present in a substantially central region in the thickness direction of the base sheet 1, and the particles are formed on the surface of the base sheet 1. 12 (one ply) having a structure in which 12 does not substantially exist. The base material sheet 1 has layers 11 and 13 of hydrophilic cross-linked bulky cellulose fibers 11a on the front and back sides of the site where the superabsorbent polymer particles 12 are present. The crosslinked bulky cellulose fiber 11a had a fiber roughness of 0.22 mg / m and an average fiber length of 2.5 mm. The layers 11 and 13 of the crosslinked bulky cellulose fiber 11a further contain a softwood bleached kraft pulp and a paper strength enhancer (PVA). A superabsorbent polymer having an average particle size of 340 μm was used. The basis weight of the layer 11 was 30 g / m ² , and the basis weight of the layer 13 was 20 g / m ² . Therefore, the basis weight of the base material sheet 1 was 80 g / m ² . The basis weight of the superabsorbent polymer 12 contained in the base sheet 1 was 30 g / m ² .

(3) Production of heating element and heating tool The aqueous electrolyte solution was dropped from a dropping nozzle toward one surface of the base sheet made of a continuous long material. The spraying basis weight of the aqueous electrolyte solution was 80 g / m ² .
Subsequently, the said coating material was continuously coated toward the surface where the electrolyte aqueous solution of the said base material sheet which consists of a continuous long thing was dripped. The coating basis weight of the paint was 1,150 g / m ² . After coating, suction was performed from the other surface side of the base sheet. However, water in the paint did not escape from the non-coated surface side of the base sheet.
Subsequently, the base material sheet which consists of a continuous long thing with which the coating material was applied was cut | disconnected over the width direction, and the heat generating body 10 was obtained.
The cut base sheet was a 50 mm × 50 mm rectangle.

The electrolyte aqueous solution sprayed on one surface of the base material sheet 1 in the electrolyte addition unit 30 has a saturated absorption amount of the superabsorbent polymer measured using the electrolyte aqueous solution 3 using JIS K 7224. It was 6.9 g / 10 minutes per 1 part by weight of the polymer. The application (addition) basis weight of the aqueous electrolyte solution 3 was 80 g / m ² , which was larger than the amount obtained by multiplying the saturated absorption amount of the superabsorbent polymer by the mass of the superabsorbent polymer contained in the base sheet 1.

The coating (coating) basis weight of the coating material 2 applied toward the addition surface of the electrolyte solution of the base material sheet in the coating material coating unit 20 was 650 g / m ² . When the base material sheet 1 was transported in the paint coating unit 20, the suction box 23 was operated to stabilize the transport and suck the coated paint 2.

  The obtained heating element 10 was cut as described above to form each leaf, and the entire heating element 10 was covered with the first covering sheet 4 and the second covering sheet 5. At this time, the side where the heat generating layer is formed in the heating element 10 is covered with the first covering sheet 4, and the side where the heating layer is not formed in the heating element 10 is covered with the second covering sheet 5. . Next, the extending portions of the first and second cover sheets 4 and 5 extending from the front, rear, left and right of the heating element 10 were joined by heat sealing. This joining was a continuous airtight joining surrounding the heating element 10. The seal width was 5 mm.

As the first covering sheet 4, a polyethylene porous sheet having a basis weight of 50 g / m ² and an air permeability of 2500 s / (100 ml · 6.42 cm ² ) was used. As the second cover sheet 5, a non-ventilated sheet made of a polyethylene film having a basis weight of 30 g / m ² was used. Moreover, each coating sheet 4 and 5 was a 65 mm x 65 mm rectangular thing.

  As a result of measuring each moisture content by the above-mentioned method, the moisture content of the sheet 1 after addition of the aqueous electrolyte solution is 65%, and the moisture content of the heating element 10 before coating with the first coating sheet 4 after coating is 40%, and the moisture content of the heat generating layer of the heating element 10 was 32%. The water content of the sheet 1 after the addition of the aqueous electrolyte solution is measured in the same manner as the method for measuring the water content of the heating element described in paragraph [0034] above.

Temperature measurement was performed by a test method based on a JIS S4100 disposable warmer temperature characteristic measurement heat apparatus. The obtained heating tool 100 was inserted into a needle punched nonwoven fabric bag having a basis weight of 100 g / m ² and placed on a constant temperature bath at 40 ° C. to evaluate temperature characteristics. This bag is formed into a bag shape by sealing three sides of the needle punched nonwoven fabric. The thermometer is disposed between the heating tool 100 and the surface of the thermostatic chamber. The heating tool 100 was placed so that the side on which the heat generation layer was formed faced upward (the direction opposite to the thermometer). As a result, the maximum temperature reached 58 ° C. 8 minutes after the start of measurement.

DESCRIPTION OF SYMBOLS 1 Base sheet 10 Heat generating body 11 Layer of hydrophilic fiber 12 Particle of superabsorbent polymer 13 Layer of hydrophilic fiber 100 Heating tool

Claims (4)

A method for producing a heating element, wherein a layer of a heat generating composition containing particles of an oxidizable metal, an electrolyte and water is provided on a base sheet made of a fiber sheet containing particles of a superabsorbent polymer and a fiber material. ,
An electrolyte addition step of adding an electrolyte aqueous solution containing the electrolyte to one surface of the base material sheet, and a coating material containing particles of the oxidizable metal not containing the electrolyte on the addition surface of the electrolyte aqueous solution in the base material sheet It has a coating process for coating ,
The method for manufacturing a heating element, wherein the coating step is a step performed after the electrolyte addition step . The electrolyte aqueous solution added in the electrolyte addition step is the superabsorbency contained in the base sheet in the saturated absorption amount of the superabsorbent polymer measured using JIS K 7224 using the electrolyte aqueous solution. The method for producing a heating element according to claim 1 , wherein a larger amount of the aqueous solution is added than the amount multiplied by the mass of the polymer. The manufacturing method of the heat generating body of Claim 1 or 2 which attracts | sucks from the other surface side of the said base material sheet after application | coating of the said coating material to the addition surface of the said electrolyte aqueous solution. A heating element manufacturing step for manufacturing a heating element by the method for manufacturing a heating element according to any one of claims 1 to 3 , and a covering step for covering the entire heating element with a packaging material, wherein the heating element is the package. A heating device manufacturing method for manufacturing a heating tool surrounded by a material,
A method for producing a heating tool, wherein the layer of the heat generating composition does not have fluidity before the heating element is coated with the packaging material.

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